Secondary School (English Medium) (5 to 8) इयत्ता ८ - CBSE Question Bank Solutions for Science

Mention against the following whether regular or diffused reflection will take place when a beam of light strikes. Justify your answer in this case.

Piece of paper

Unscramble the jumbled word underlined in the following statement.

Yeasts are used in the wine industry because of their property of meronettinaf

Name one commercial use of yeast.

In the soil, which nutrient is enriched by blue-green algae (cyanobacteria)?

Give reason for the following.

Fresh milk is boiled before consumption while processed milk stored in packets can be consumed without boiling.

Give reason for the following.

Raw vegetables and fruits are kept in refrigerators, whereas jams and pickles can be kept outside.

Give reason for the following.

Mosquitoes can be controlled by preventing stagnation of water though they do not live in water. Why?

How can we prevent the following diseases?

Hepatitis A

Rohit took with him some nylon ropes, when he was going for rock climbing. Can you tell why he selected nylon ropes instead of ropes made up of cotton or jute?

Metals generally react with dilute acids to produce hydrogen gas. Which one of the following metals does not react with dilute hydrochloric acid?

Which of the following reacts with cold water vigorously?

Zinc sulphate forms a colourless solution in water. Will you observe any colour on adding copper turning in it?

The calorific value of a fuel is expressed in a unit called

In villages, people use wood as fuel because

Which among the following is considered as the cleanest fuel?

Choose the incorrect statement from the following.

A good fuel is one which

State whether the following statement is True or False.

Calorific value of wood is higher than that of coal.

Write True/False against the following statement and also correct the false statement.

Greater the calorific value, better is the fuel.

Give two examples each for a solid, liquid and gaseous fuel along with some important uses.

Although wood has a very high calorific value, we still discourage its use as a fuel. Explain.